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A prime number (or prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself. By Euclid's theorem , there are an infinite number of prime numbers. Subsets of the prime numbers may be generated with various formulas for primes .
The Liouville function λ(n) is 1 if Ω(n) is even, and is -1 if Ω(n) is odd. The Möbius function μ(n) is 0 if n is not square-free. Otherwise μ(n) is 1 if Ω(n) is even, and is −1 if Ω(n) is odd. A sphenic number has Ω(n) = 3 and is square-free (so it is the product of 3 distinct
Perfect number. In number theory, a perfect number is a positive integer that is equal to the sum of its positive proper divisors, that is, divisors excluding the number itself. For instance, 6 has proper divisors 1, 2 and 3, and 1 + 2 + 3 = 6, so 6 is a perfect number. The next perfect number is 28, since 1 + 2 + 4 + 7 + 14 = 28.
Palindromic number. A palindromic number (also known as a numeral palindrome or a numeric palindrome) is a number (such as 16461) that remains the same when its digits are reversed. In other words, it has reflectional symmetry across a vertical axis. The term palindromic is derived from palindrome, which refers to a word (such as rotor or ...
A prime number (or a prime) is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 4 is composite because it is a ...
An abundant number which is not a semiperfect number is called a weird number. An abundant number with abundance 1 is called a quasiperfect number, although none have yet been found. Every abundant number is a multiple of either a perfect number or a primitive abundant number. Related concepts Euler diagram of numbers under 100:
Using all numbers and all letters except I and O; the smallest base where 1 / 2 terminates and all of 1 / 2 to 1 / 18 have periods of 4 or shorter. 35: Covers the ten decimal digits and all letters of the English alphabet, apart from not distinguishing 0 from O. 36: Hexatrigesimal: Covers the ten decimal digits and all letters of the English ...
The percentage of odd numbers clearly becomes very low and the percentage of even numbers seems to approach 100. If we look at the formula and let n →∞, So 100% of the numbers are even, (although they are not)! n % odd % even n % odd % even 1 100 0 11 8.4 91.6 2 90 10 12 6.3 93.7 3 75 25 13 4.8 95.2 4 59.6 40.4 14 3.6 96.4 5 46 54 15 2.7 97.3